About 50% of all cases of combined deafness and blindness is due to Usher syndrome. Recent advances in molecular genetics has enabled the isolation and characterization of two Usher genes, USH1B and USH2A. There remain possibly as many as eight other genes that cause Usher syndrome. Further research into their identification and characterization will enhance diagnostic accuracy, improve genetic counseling, and present a real promise of more effective methods of therapy. Importantly, the knowledge gained from these studies will provide a foundation for better understanding of the molecular biology of the auditory and visual systems and their interrelationships. Progression from gene localization to the study of the expression of an individual gene required to carry out all stages of the process and continues to build upon experience gained in the first two 3 year cycles of the current Program Project. This renewal application proposes 4 related projects that will advance understanding of Usher syndrome. The continuation of this program will maintain existing professional relationships and will foster further collaboration within an already successful and integrated team of scientists. Project 1 will study genetic mapping and basic epidemiological aspects of Usher syndrome. Project will investigate the functional aspects of the novel usherin protein now know to be involved in Usher type IIa; Project 4 will study clinical issues concerning Usher syndrome. Three cores are also proposed: Administrative, Genetic Analysis, and Technical. This PPG brings together diverse investigators to meet a common goal: the further understanding of the genetic basis of Usher syndrome. it has already fostered close collaboration and promises continued productive collaborations in the future. The existence of as many as 10 genes whose mutations result in similar disorders of both the auditory and visual senses offer a rare opportunity for study that promises to greatly advance our understanding of the molecular genetics of the sensory systems.